Oil sands deposits close to the surface can be extracted in an open-cast system if necessary, with processing to separate the oil subsequently being required. However “in-situ” methods are also known in which, by introducing “solvent” or thinning agents and/or alternatively by heating up or melting the very heavy oil the deposit is made flowable while still in the reservoir. The “in-situ” methods are especially suitable for reservoirs which are not close to the surface.
The most widespread and widely-used “in-situ” method for extracting bitumen is the SAGD (Steam Assisted Gravity Drainage) method. In this method, steam, which can be added to the solvent, is injected at high pressure through a pipe running horizontally within the reservoir. The bitumen heated-up, melted or dissolved from the sand or rock seeps down to a second pipe located around 5 m (distance between injector and production pipe depends on reservoir geometry) through which the liquefied bitumen is extracted. In this method the steam has a number of tasks to perform, namely the introduction of heat energy for liquefaction, the removal of sand and building up the pressure in the reservoir, in order on the one hand to make the reservoir porous for the transport of bitumen (permeability) and on the other hand to make it possible to extract the bitumen without additional pumps.
The SAGD method starts by both pipes being heated up by steam, typically for 3 months, in order to initially liquefy the bitumen in the space between the pipes as quickly as possible. Then steam is introduced into the reservoir through the upper pipe and extraction through the lower pipe can begin.
A method for resistive heating up of a very heavy oil deposit is known from US 2006/0151166 A1, in which a tool with electrodes for a three-phase resistive heating of the deposit is provided for reducing the viscosity of the very heavy oil. With the applicant's older, not previously published German patent applications AZ 10 2007 008 292.6 entitled “Vorrichtung and Verfahren zur in situ-Gewinnung einer kohlenwasserstoffhaltigen Substanz unter Herabsetzung deren Viskosität aus einer unterirdischen Lagerstätte (apparatus and method for in-situ extraction of a substance containing hydrocarbons from an underground deposit while reducing its viscosity)” and AZ 10 2007 036 832.3 entitled “Vorrichtung zur in situ-Gewinnung einer kohlenwasserstoffhaltigen Substanz (apparatus and method for in-situ extraction of a substance containing hydrocarbons)” electrical/electromagnetic heating methods for an “in situ” extraction of bitumen and/or very heavy oil have already been proposed in which in particular an inductive heating of the reservoir is undertaken.
Using the prior art as its starting point, the object of the invention is to create an apparatus with a suitable design for electrical/electromagnetic heating of the reservoir of an oil sands deposit.